LC Urgent Q1: Urgent measures to ensure structural safety of roofs with green vegetation

Following is an urgent question by the Hon Chan Hak-kan under Rule 24(4) of the Rules of Procedure and a reply by the Acting Secretary for Development, Mr Eric Ma, in the Legislative Council today (May 25):


In the afternoon of the 20th of this month, the entire roof of the Chan Tai Ho Multi-purpose Hall at the City University of Hong Kong collapsed abruptly, injuring three persons. There are views that the accident may be attributable to the roof being covered by green vegetation and thus being overloaded. In this connection, will the Government inform this Council whether it will launch urgent measures immediately to ensure the structural safety of all roofs with green vegetation in Hong Kong, so as to safeguard public safety; if it will, of the details; if not, the reasons for that?



The Government is very concerned about the roof collapse incident occurred at the City University of Hong Kong last Friday. Right after the incident, the Buildings Department (BD) has immediately deployed its staff to the scene for site inspection to confirm that other structures of the building pose no immediate danger. The BD has also started its investigation into the cause of the roof collapse soon afterwards, and will strive to come up with some initial findings in two weeks' time.  Detailed investigation involves collecting evidence and testing of construction materials. As the relevant specimen can only be taken after the stabilisation works and other works at the scene have finished, detailed investigation results are expected to require more time.

At the same time, the Development Bureau has convened an inter-departmental meeting with government departments concerned to consider measures on various fronts in order to avoid recurrence of similar incidents. Amongst such measures, the Architectural Services Department (ArchSD) will carry out inspection of government facilities by phases based on its risk assessment, with priority inspections already conducted in respect of greening facilities above long-span metal structures. Greening facilities on other concrete rooftops will be progressively inspected thereafter.  According to the ArchSD's records, amongst the government facilities of which it is responsible for maintenance, there are four greening facilities installed over long-span metal structures, namely the Ping Shan Tin Shui Wai Swimming Pool, the Victoria Park Swimming Pool, the Sai Kung Tseung Kwan O Government Complex, and the New Wing of the Ko Shan Theatre. The ArchSD has finished inspection of the four facilities, all of which were found in normal conditions. At the same time, the Housing Department has conducted inspection and assessment on all the eight retrofitted green roofs in public housing estates, and its initial assessment is that the risk is not high.

For private buildings, the Government has in place different levels of regulatory control over roof greening. If the greening only involves placing of a few flower pots, it generally will not cause any risk. If the greening is of a substantial scale, the relevant owner should then consult authorised building professionals on matters such as roof loading. The building professionals authorised by the BD possess professional expertise.  They should advise the owners, where the greening involves building works, on the need for seeking the BD's consent for the works depending on their location, scope and extent. For works requiring the BD's prior approval, the BD will assess the works proposed and will only give its consent for commencement if it is satisfied with the safety of the works. Generally speaking, greening works at rooftops should pose no risk to safety if the roof loading has been evaluated by building professionals and that there are proper maintenance and repairs. For roof greening works on new buildings, they have been taken into account at the building design and the plan approval stages, with evaluation conducted by the building professionals and approval given by relevant authorities. The public do not have to worry too much about their safety.

For existing buildings, in view of the roof collapse incident, relevant departments will ascertain through various channels whether any green roof of large areas might have been carried out without prior evaluation by building professionals. Immediate actions will be taken against any such case found. Measures include:

(1) the BD has disseminated information to post-secondary institutions as well as secondary and primary schools through the Education Bureau, providing advice on the installation of green roofs for ensuring safety of the school premises and the occupiers;

(2) the BD will issue a circular to the industry within this week to set out the circumstances under which roof greening may constitute risk and request immediate follow-up actions to be taken by the industry and building owners; and

(3) the BD and other relevant departments will shortly arrange a series of briefings for school administrators and relevant stakeholders, to explain the matters warranting their attention when carrying out roof greening works, how existing green roof should be managed, etc, and to answer their enquiries.

Ends/Wednesday, May 25, 2016
Issued at HKT 19:31